1. Field of the Invention
The present invention relates to a jig. More particularly, this invention relates to a jig with which a positioning work of a retaining ring of a seal ring relative to a blade ring of a turbine can be performed easily with high accuracy.
2. Related Art Statement
FIG. 9 is a schematic diagram of a conventional jig 200. A gap between a blade ring 10 of a turbine and a seal fin (not shown) of a turbine disk is sealed with a seal ring 11. The seal ring 11 is retained by a retainer ring 12 and is arranged around an inner periphery of the blade ring 10.
Disassembling and reassembling works for the blade ring 10, the seal ring 11, and the retainer ring 12 are necessary during maintenance of the turbine (for example, when replacing stator vanes 101 that constitute the blade ring 10). In the reassembling work, positioning (aligning) work of the retainer ring 12 relative to the blade ring 10 is performed. If the positioning of the retainer ring relative to the blade ring 10 is appropriate, an inappropriate gap is produced between the seal ring 11 and the seal fin, so that sufficient sealing performance can not be achieved. Rubbing due to eccentricity of the seal ring 11 may occur when a rotor rotates. Therefore, there is a demand that positioning of the retainer ring 12 relative to the blade ring 10 is performed with high accuracy.
At the positioning work of the retainer ring 12 relative to the blade ring 10, a distance between a measurement point (a reference point) on the side of the blade ring 10 and a measurement point on the side of the retainer ring 12 is measured on a plurality of points on the blade ring 10. The installation position of the retainer ring 12 relative to the blade ring 10 is fine-adjusted by taking into account the measurement values. The jig 200 that is an exclusive measuring device is used to perform the measurement (see FIG. 9). The conventional jig 200 includes a base 201, a shaft 202, a probe 203, and a measuring unit 204. When performing the measurement, the base 201 is placed on an edge of an outer peripheral side of the blade ring 10 to determine a measurement point (a reference point) on the side of the blade ring 10. The shaft 202 is fixedly mounted on the base 201 such that it extends toward an inner side in a radial direction of the blade ring 10. The probe 203 is mounted on the tip of the shaft 202 and determines a measurement point on the side of the retainer ring 12. The measuring unit 204 consists of, for example, a dial gauge and is arranged together with the probe 203 on the tip of the shaft 202.
However, in the conventional jig 200, because the measuring unit 204 is mounted on the tip of the shaft 202, the shaft 202 may be deflected by the weight of the measuring unit 204. Consequently, accurate measurement can not be performed, or the operator of the jig 200 must be highly skilled. Moreover, measurement results may vary depending on the operator.
There have been no published patent documents that disclose a jig for positioning a blade ring of a turbine and a retaining ring.